Approximately 75,000 to 150,000 patients/year with angina have normal coronary arteries by angiography. Although cardiac events are rare, these non-cardiac chest pain (NCCP) patients have chronic pain, limited lifestyles and excessive health care use (> $500 million/year). Esophageal diseases (acid reflux or motility disorders) are common in NCCP patients suggesting a casual relationship. However, this correlation has been difficult to prove and studies suggest that psychosocial factors may contribute to their pain reports as seen in irritable bowel syndrome (IBS). Utilizing a multi-discipline approach, we will investigate the psychophysiological interaction contributing to NCCP. Our goals are three: 1) A prospective case comparison study will assess the psychosocial factors associated with NCCP by a series of standardized inventories and a structured interview. These factors will include affective responses, functional disability, pain perceptions, pain coping strategies, and environmental stressors. NCCP patients with varying degrees of esophageal abnormalities will be compared to healthy controls, patients with organic chest pain (angina and esophagitis) and patients with chronic GI pain without organic disease (IBS). 2) Since abnormal pain perception may contribute to NCCP, patients will be assessed for their general and organ specific pain threshold levels and a sensory decision theory analysis will determine if group differences may be due to discrimination abilities, response biases or both. It is hypothesized that significant differences will be found between NCCP and IBS patients relative to the control subjects with regard to psychological distress, susceptibility to gastrointestinal symptoms under stress, major and minor environmental stressors, and responses to balloon distention stimulation of the esophagus. If our hypotheses are supported, these experiments will provide evidence that NCCP and IBS patients represent a GI spectrum of psychophysiological dysfunction - the Irritable Gut; there will be strong evidence that these patients' pain perceptions are related to a tendency to overly focus on somatic stimuli arising from the GI tract (Experiment 2) and that this hypervigilence may contribute to their high levels of psychological distress (Experiment 1).